The main purpose of this study is to investigate the precipitating situational factors for the psychosocial vulnerability of Korean immigrants in their various adaptation stages. Specific aims are: (1) to identify the high-risk stages in which Korean immigrants are generally vulnerable to mental and behavioral disorders, and (2) to investigate precipitating factors associated with the high-risk stages for developing possible intervention programs. The general theoretical contention is that in view of migration as a process the nature and extent of immigrants' mental health problems vary with their adaptation stages, and that there are certain critical stages in which immigrants become generally vulnerable to mental and behavioral disorders. To examine this theoretical model, a specific hypothesis is advanced: Korean immigrants face two critical stages in which their mental would become highly vulnerable -- the early exigency stage (1-2 years after immigration) and the later relative deprivation/marginality stage (11-15 years after immigration). This hypothesis is tested through an epidemiological survey (diagnostic interviews for assessing the degree of demoralization/distress) of three groups of Korean immigrants in different adaptation stages -- the early exigency, the intermediate, and the later relative-deprivation/marginality stages. The significance of this proposal is that immigrants' mental health problems may be identified by the process model (differential sources of stress impacting on mental health at various stages of migration), and that the problems may be prevented by intervention programs. This research thus purports to generate not only theoretical but also practical implications for effective intervention strategies toward primary intervention of mental health problems among Korean immigrants in particular and Asian immigrants in the U.S. in general.